OFFSET
1,1
EXAMPLE
For the first two digits, none of 1, 6, and 16 are prime.
The next digit, 1 is not prime, but 61 is, so a(1) = 61. 161 is not prime, so it is not included.
PROG
(PARI) v=[1, 6, 1, 8, 0, 3, 3, 9, 8, 8, 7, 4, 9, 8, 9, 4, 8, 4, 8, 2, 0, 4, 5, 8, 6, 8, 3, 4, 3, 6, 5, 6, 3, 8, 1, 1]
for(n=1, #v, x=0; p=1; forstep(k=n, 1, -1, x+=p*v[k]; p*=10; if(v[k]&&isprime(x), print1(x", "))))
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Franklin T. Adams-Watters, Oct 21 2011
STATUS
approved